auto save

diy2.py

+username = "python"
+userpassword = "123456"
+while True:
+    name = input("请输入用户名:")
+    password = input("请输入密码:")
+    if name == username and password == userpassword:
+        print("登录成功!")
+        break
+    elif name!=username and password !=userpassword:
+        print("用户名不存在，请重新输入")
+    else:
+        print("密码错误，请重新输入")
+    
+print("欢迎来到贝尔编程!")
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